1. Field of the Invention
This invention relates an apparatus for applying a treatment to semiconductor materials such as silicon wafer or glass photomask, and more specifically to a square basin for applying a treatment such as etching, development, plating or washing to surfaces of semiconductor materials housed in a carrier.
2. Description of the Prior Art
In a commonly accepted technique, a basin of the above sort is shaped square for receiving therein an essentially square carrier for semiconductor materials, and is provided at a bottom portion thereof with a passage for introducing a treatment liquid thereinto. A gutter is located on an outer portion of the top periphery of the basin to receive overflown treatment liquid. Treatment liquid introduced through the passage in the bottom is overflown a top periphery of the basin, and then received in the gutter. The thus-received treatment liquid is again sent to the introduction passage through a circulating passage including a pump, so as to circulate the treatment liquid. Semiconductor materials housed in a carrier supported in a basin are treated with thus-circulating treatment liquid.
Since a treatment liquid is introduced upwardly through the bottom passage of a basin and then overflown top periphery of the basin, treatment liquid flows actively in the central and upper zones in the basin, while in the peripheral and lower zones in the basin it flows weakly and local stagnations will be caused. These provide inequal contact of semiconductor surfaces with the treatment liquid, which results in inequal treatment.